I've been at this for quite some time now, not really getting it to work. Unfortunately I am only able to test on our Office365 account and changes take forever to propagate so I can test after changing rules..

The problem is as follows

My organisation wants a centralised signature added to all emails (this is easily fixed by adding a transport rule and "append a disclaimer ...")

Here is the kicker however, when the mail is sent as text/plain the nicely formatted HTML signature is wrapped (thats what we decided to do, so a signature is added at least) but it look horrible.

Is there any way of finding out if the mail is text/plain and then adding one signature and another if the mail is sent as HTML?

I've been playing around with rules and checking in the headers for Content-Type and trying to match against that but so far, no luck.

I believe Office365 runs Exchange 2010.

edit Found the following on the Microsoft boards after some more digging:

.. this would only work if you set your email to use POP or IMAP. Otherwise the content-type will not be viewable by the transport rule, and would therefore not work.

That explains why my attempts to look for Content-Type header failed..


The short answer is that Exchange transport rules are just simply not flexible enough to handle the signature needs of most organizations, as you have found. The problem with searching email content with transport rules is that they search the rendered body, not the raw body. So if you're looking to match a MIME part header, you're out of luck.

At this point, you probably need to consider a third-party signature management product. See Better Signature Management (Exchange-bound?)

  • Unfortunately we are on Office365 :( – hank Feb 13 '13 at 16:03
  • Doh! I completely missed that part. Sorry. – longneck Feb 13 '13 at 16:04
  • Wait, Exclaimer does support Office 365 because it will update OWA signatures. You should check it out! – longneck Feb 13 '13 at 17:18
  • Indeed it does, I will have to look closer into it - Lesson learned, you shouldn't dismiss stuff too fast! – hank Feb 13 '13 at 18:44

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